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This paper considers the integrated approach to modeling the dynamics of genetic structure and the number of natural population. A set of dynamic models with different types of natural selection is used to describe a possible mechanism for the fixing of a genetic diversity in size of the litter in coastal, continental and farmed populations of arctic fox (Alopex lagopus, Canidae, Carnivora) observed now. The most interesting results have been obtained with the model of population consisting of two stages of development. At that with the frame of this model a dynamics of population genetic structure on genotypes was analyzed to consider different reproductive abilities and fitnesses of pups on the early stage of lifecycle which defined by the single diallelic gene. This model allows to receive a monomorphism for coastal populations of arctic fox, where food resources are practically constant. As well the model allows polymorphism with cyclical fluctuations in the number and frequency of the gene in the continental populations due to regular fluctuating of rodent number, the major component of its food. In farmed populations by selective selection carried out by farmers to increase the reproductive success, this gene is a pleiotropic one (i. e., determining the survival rate of individuals both early and late stages of their life cycle); so an application of appropriate model (with the selection of pleiotropic gene) allows to get an adequate rate of elimination for small litters allele.

This paper studies a model of a population with non-overlapping generations and density-dependent regulation of birth rate. The population breeds seasonally, and its reproductive potential is determined genetically. The model proposed combines an ecological dynamic model of a limited population with non-overlapping generations and microevolutionary model of its genetic structure dynamics for the case when adaptive trait of birth rate controlled by a single diallelic autosomal locus with allelomorphs A and a. The study showed the genetic composition of the population, namely, will it be polymorphic or monomorphic, is mainly determined by the values of the reproductive potentials of heterozygote and homozygotes. Moreover, the average reproductive potential of mature individuals and intensity of self-regulation processes determine population dynamics. In particularly, increasing the average value of the reproductive potential leads to destabilization of the dynamics of age group sizes. The intensity of self-regulation processes determines the nature of emerging oscillations, since scenario of stability loss of fixed points depends on the values of this parameter. It is shown that patterns of occurrence and evolution of cyclic dynamics regimes are mainly determined by the features of life cycle of individuals in population. The life cycle leading to existence of non-overlapping generation gives isolated subpopulations in different years, which results in the possibility of independent microevolution of these subpopulations and, as a result, the complex dynamics emergence of both stage structure and genetic one. Fixing various adaptive mutations will gradually lead to genetic (and possibly morphological) differentiation and to differences in the average reproductive potentials of subpopulations that give different values of equilibrium subpopulation sizes. Further evolutionary growth of reproductive potentials of limited subpopulations leads to their number fluctuations which can differ in both amplitude and phase.